I'm using Flash Builder 4 and the Flex API 4 and until yesterday all was well - i.e. I could run my app in debug mode. Somehow today things stopped working. Not sure why - I didn't tweak anything in Flash Builder's options. When launching any app (most complicated to the simplest) I get a status bar telling me

Thank you for your help. Unfortunately I've tried all three and had no luck. In fact, I've tried to create a new super simple project that has 1 button and does nothing and the debugger won't work there either.

Interestingly enough, I just found out that if I run stuff in Flash Player, all is fine. I'm starting to suspect that chrome is automagically updating its built in flashplayer to a non-debug version. I wonder...

So, I guess I'm going to use the debugger in Flash, but would still love to know if anyone has any idea of how to fix this in Chrome.

Hopefully Adobe is reading this. I've had this exact same problem since FlexBuilder v3. It's extremely frustrating. I have also experienced this with multiple versions of Firefox and IE all running debugger Flash players, and it has happened about 10 times so far this morning. Restarting Flash Builder sometimes lets me do maybe two or three builds before it happens again. I'd appreciate a more detailed report from Adobe on what exactly is the problem, especially since it is a huge time waster.

Yes, this is a specific bug that's been around a long time. I've experience this on multiple machines and many different browsers. I also thought I had opened a ticket several years ago and got the same answers that only provided temporary fixes: e.g. re-install project, re-install Flash/FlexBuilder etc.

- Where do I go to officially file a bug? Do I have to have a support contract with Adobe to do this?

- Can you please provide a link to the "flashlog.txt" post? I searched for it and didn't find anything from yesterday.

sorry - i never posted more on this after I figure out what had happened.

Basically somehow chrome - my browser of choice - automagically updated my flash version to a non debug one, without telling me anything, overnight. So, one day the debugger was working and the next it wasn't.

I would start by using one of the many sites that can tell you if your browser still has a debug version of flash installed. If so, then I don't think you're suffering from the same problem I was suffering from. If not, you can do two things:

- debug in flash: I now simply run all my apps in flash while I develop. It's a lot more of a controlled environment, works like a charm, the debugger is on, etc.

- fix the flash install on your browser: I ended up skipping this in fear of messing things up more but I think it's probably not that hard.

I believe I figured out my problem and it's a bit different. I definately have debugger versions of Flash Player installed. If I stopped a debug session from within FlashBuilder 4.0.1 everything seems to be working fine. HOWEVER, if I stopped a debug session by simply closing the browser tab, then in most instances the very next debug session failed to launch. I've been able to duplicate this on 4 different machines. Since Adobe never responded to my questions above for additional details on where/how to file a bug, I have not filed this as a bug. I hope this helps someone else.

I get this issue ~ 40 times a day and it is extremely frustrating. I have tried reinstalling flash builder, uninstalling anything that I think might affect it (fiddler & servicecapture), and have tried chrome, firefox, and internet explorer as my default browser for flex to no percievable difference. The only recourse is to force a project clean and rebuild - which is absolutely horrible as the app I work on is ******* huge and basically adds about 2 minutes everytime i want to do a build. Soooo frustrating....

I think I can help because I had the same problem and I spent a lot of hours trying to fix the problem. I tried several solutions but none of them worked. The problem is that the Flash Player in the browser hasn't debugging capabilities. The link mention earlier, http://flashplayerversion.com/, is a really good one to check if your browser's Flash Player has this feature.

The first link will install debugger player for your IE and the second one for your Firefox. I think it's a bit misleading to mention "Netscape" nowadays, it should be switched to Firefox.

Because Chrome has the Flash Player integrated (which is GREAT) it does, however, cause more problems to get a debugger player for it. However, as long as I have at least one browser that makes debugging in Flash Builder function -- I'm happy!

One last thing, in Flash Builder make sure your web browser in Preferences is one that has a debugging supported browser. Go to Window > Preferences and choose General > Web Browser. Make sure the browser is either IE or Firefox. I also tried with Opera (v. 10.63) and it had the debugged version of Flash Player. So, Google just needs to do add a little improvement that developers can have a debugged player and everything is perfect.

I have a problem when running debug in my Flash Builder 4. When i click on the debug button, when it launch i have ERROR 404 showing up in my browser.

I have check the debug folder path and compare it with the browser they are the same. I noticed that the index.html is missing. Then i tried to copy the index.html from my release folder and somehow it run. But the when i run the debug again, it shows the ERROR 404 in my browser. Somehow it deleted the index.html that i copied from the release folder.

Well that's your problem. You should have a index.template.html file in there. I'm not sure how you would regenerate this, but try going to Project -> Properties -> Flex Compiler and then try changing around some of the settings for HTML Wrapper. This should trigger a regeneration of that file.

Thanks for the advice, it works. But its very strange, because when i checked the flex compiler properties, the Generate HTML-Wrapper File is enable. What i did is, i disable it then enable it back, and whoala.. it generate the html file. Is this a bug or something?

I downloaded and tried to install Adobe Flash player, but then when i tried i still have this error. I check the path and found out that the Flash Player.plugin is in the correct directory. Below is the directory captured image.

Just an FYI, for anyone encountering the issue where the debugged sporadically connects to the browser debugger... Download the flash projector (stand alone) debugger. Edit the projects debug settings and in the url to debug change the .html to .swf. Instead of luanching in a browser it will launch in the stand alone flash projected application and connect every time. Happy Coding. For even more awesomeness use HellFire Daemon Compiler... its freaking insane!

Thanks for the advice... my bad.. i just noticed that my FP is without a dubugger plugin.. stupid of me. LOL.. i managed to download the plugin with debugger and it works ok... Im still new and trying to learn programming.

I ran into the same issue today and found this page while searching for help.

None of the suggestions helped. But there was a suggestion to debug in flash itself. So I opened the .html file from bin-debug in the flash builder itself - basically double click, and it worked in the builder. Now the surprising part is I had not closed the applications I'd started for debug, these were still stuck at 57%. These started opening in my browser with debugger version of flash player!! And it was debugging fine!

Guess the trick is to click on the .html file while the progress bar is stuck at 57% for debugging the application. No clue why this works.. I have tried this 2-3 times and it worked always.

The Flash Builder debugger failed to connect to the running application.Ensure that: 1. For in-browser applications, you are running the debugger version of Flash Player. 2. For network debugging on a mobile device, you have a reliable network connection to the device, and port 7935 is open on your machine's firewall. Device connection help

Flash Player is really got nothing to do here since i'm trying to debug Air apps.

Debugging worked fine with Flex sdk 4.5 and air sdk 2.6.

After updating to air 2.7 and sdk 4.5.1 i couldn't debug any Air app, mobile or not (although i can debug on the mobile device, however it's a pain to always debug on the device, it's just a waste of time)

I have encountered this situation many times in Flash Builder 4.5 and it always seems to occur when, prior to launching the application from the Builder I was using phpadmin (wampserver) and failed to close this application in the browser before staerting the debugger.

I'm having the exact same problem that pin05h is having - debugging in AIR, Flash Builder hangs at 57%, get the same error message every time, not running phpadmin or wampserver. However, when I debug the application, not only do I have nowhere to right click and say Connect (the window does not appear until the error does), but the error only lasts 3 or 4 seconds.

How do I specify that I want the app to run in the browser? And, if we are using AIR-only features (which I'm not sure I am), how do we fix the debugging issue there? Thanks for working to fix this issue.

I'm facing same issue, "Failed to connect;session time out". For the background, I'm using FB 3 and IE . A strange thing is happening in my Flex Builder though, for one application the debugger is working successfully but for the other its giving this error at 91% launch.